1. Field of the Invention
The invention relates to a clip of thermoweldable material for a conduit also comprised of weldable material, such as a repair clip, comprised of at least two shells surrounding the conduit in the position of use, of which optionally at least one has a branch pipe, and wherein the shells have longitudinal flanges facing one another in pairs in the position of use, which can be connected to one another under pressure, wherein the shells have at least one electrically heatable conductor arranged in continuous windings at its inner surfaces, and wherein the windings of the conductor extend, on the one hand, only in a semi-circular zone at the inner surfaces in the two end areas of the shell, respectively, and, on the other hand, extend also between these two semi-circular zones in a planar strip. Such clips are used, for example, for repair purposes or to retrofit an already mounted conduit, that is pressurized by a medium, with a branch conduit. In the latter situation, clips are used which have a branch pipe at least at one of the cylinder-shaped shells placed about the conduit. This branch pipe first serves to drill into the conduit, but then also to guide the medium into the branch conduit connected to the branch pipe. In the first situation, where a conduit has a defective location, the clip comprised of shells without a branch pipe is placed onto the conduit for repair purposes.
2. Description of Related Art
A known clip of this kind (DE 295 12 309 U1) has windings of a conductor provided on the inner surfaces of the two shells wherein only those circular zones in which the branch pipe is provided are free out such windings. The conductor is a wire whose windings are comprised of parallel linear winding legs and winding arches connecting them in pairs. The great length of the conductor requires great electrical energy expenditure for melting the contact surfaces. In the large contact area to be welded disturbances can occur at many locations, and this can result in leaks. The two shells of this known clip are of different design relative to one another, and there are wall areas which overlap. This requires different mold parts for manufacturing the two shells and a correspondingly complex storage and processing.
The disadvantage of a different design of the shells for forming the clip also pertains to the solution according to DE 195 19 341 C1. This is so because in this known solution the different design of the shells results from the longitudinal flanges of only one shell having a respective heating coil.
Shells of identical design are disclosed in the prior art CH 652 473 A in which, however, the heating coil is in the form of a separate component not connected to any of the shells. For the purpose of arranging the heating coil between the shells and the conduit, the inner surfaces of the shells must be spaced from the surface of the conduit by a spacing corresponding to the heating coil. Moreover, for filling this intermediate space with material, the heating wire of the heating coil is embedded in plastic material which, as a result of melting, fills the intermediate space and provides a connection between the conduit and the shell.